Z < 60- Rare earth promoted α-Si3N4 solid solution: Praseodymium

So long, larger sized rare earth cations than Neodymium (Z = 60) were reported to form α-SiAlON either in a multi-cation system containing smaller cations or by following special processing conditions. In this study, Praseodymium (Z = 59) alone is observed for the first time to promote α-SiAlON as a single crystalline phase, prepared under conventional processing conditions of heating and cooling cycle. The appearance of α-SiAlON is restricted to the compositional area corresponding to a high level substitution of m(RE1/3AlN) for m(SiN) bonds. Microstructure exhibits strain contrast in grains and array of dislocations in low angle grain boundary indicating deformation in lattice.